Adjusting means for a differential feed



Dec. 8, 1964 H. ORTH ETAL 3,160,127

ADJUSTING MEANS FOR A DIFFERENTIAL FEED Filed March 14, 1962 3 Sheets-Sheet l Dec. 8, 1964 H. QRTH ETAL 3,160,127

ADJUSTING MEANS FOR A DIFFERENTIAL FEED Filed March 14, 1962 3 Sheets-Sheet 2 BYWW Dec. 8, 1964 Filed March 14 1962 H. ORTH ETAL ADJUSTING MEANS FOR A DIFFERENTIAL FEED 3 Sheets-Sheet 3 INVENTORJ AMA/6' 0177/ 44 0 United States Patent 3,160 127 ADJUSTXNG MEANS FGR A DEFFERENTHAL FEED Hans firth, Alsenborn, and Herbert Wenz, Kaiserslautern,

Pfalz, Germany, assigners to G. M. llfaif A.G., Kaiser'slautern, Pfaiz, Germany Filed Mar. 14, 1962, filer. No. 179,613 laims priority, application Germany, Italy 20, 1961,

P 27,563 Qlaims. (til. 112-299) The invention relates to sewing machines and is particularly concerned with sewing machines of the type having a pair of feed dogs, a main feed dog and an auxiliary feed dog, each of which is provided with a stitch setting means, the positions of which are determined by the angular positions of setting shafts and wherein a spring biases the setting shaft for the main feed dog toward one direction of rotation.

In known arrangements for adjusting the differential feed the setting shafts for the main feed dog and for the auxiliary feed dog, together with abutrnents secured to them, are each tuined in the same direction of rotation by a pressure spring, fixedly mounted at one end and supported at the other end against the respective setting shaft, against fixed abutments which determine the feed length of the feed dogs. In order to insure secure engagement of the abutments which determine the feed length, it is necessary for the turning springs to be relatively strong. This involves the shortcoming that the force of two turning springs which is not negligible must be overcome if in the operation of a latch manipulator arranged at the forward end of the standard of the machine the seam is to be secured at its beginning or its end by several reverse stitches. This constitutes a handicap in the operation for the person operating the machine.

It is an object of the invention to provide an adjusting means for the differential feed which, while eliminating the foregoing shortcoming, provides for secure engagement of the abutments which determine the feed length of the two feed dogs and makes possible easy manipulation of the locking or bar stitch lever for the purpose of securing the seam as aforementioned by the bar stitches.

In accordance with the invention, this object is achieved by a coupling spring arranged in the rod connection between the two setting shafts Which elfects positive engagement of an abutment that is in contact with the setting shaft for the auxiliary feed dog against a counter abutment which has a connection with the gear rods of the main feed dog.

In this manner it is accomplished that the coupling spring merely turns the setting shaft for the auxiliary feed dog in the same angular position as that of the setting shaft for the main feed dog so that its force is not directed against the tacking lever or manipulator. When operating the said manipulator for securing the seam by several reverse or bar stitches, it is thus only necessary to overcome the force of a normal spring which presses the gearing of the setting shaft against a stitch setting abutment. This constitutes considerable relief for the seamstress in operating the sewing machine.

Advantageously the coupling spring is arranged in such a manner that its effective force is opposite to the effective force of the spring which engages the setting shaft for the man feed dog.

The coupling spring presses the setting shaft of the auxiliary feed dog into the same angular position as that of the shaft of the main feed dog against a minimum feed abutment of the auxiliary feed dog. This may be accomplished in different ways, such as with torsion springs or pull springs. By suitable pedal operation it is possible to obtain the increasing shirring which is desirable in 3,16%,i2? Fatented Dec. 8, 1964 machines of this type. The heavier the pressure on the pedal, the more shirring of the material is obtained.

Other features and objects of the invention and details of the advantages obtained will become apparent from the following description of two embodiments of the new setting device for differential feed illustrated in the attached drawings, in which:

FIG. 1 is a front elevational view of the machine;

FIG. 2 is one embodiment of the setting device for the differential feed;

FIG. 3 is a second embodiment of the new arrangement;

FIG. 4 is a perspective view of the mechanism illustrating the arrangement of the feed dogs ad of the driving means therefor; and

FIG. 5 is a view showing the coupling of FIG. 3 from the bottom taken in the direction of the arrow U.

The main setting shaft 2 for the main feed dog 35 and the auxiliary setting shaft 3 for the auxiliary feed dog 38 are journalled in the work plate 1 parallel relative to each other with a space therebetween, and are secured against axial movement by screws 6 mounted in bridge members '7 and having studs 5 extending into circumferential grooves 4 A linkage means including a linkage connecting member in the form of a two armed lever 8 is clamped onto main setting shaft 2 for the main feed dog 35 and has one arm connected to one end of a ball headed pull bar 9, the other end of which is connected to an arm of a two armed stitch setting lever 10. The latter is mounted on a stitch setting shaft 11 journalled in the arm standard and extends with a ball headed end 12 of its other arm into a cam groove 13 in a rotatable setting disk 14 and which determines the feed length of the main feed dog 35.

A torsion spring 16 biased at one end against the work plate of the machine and at the other end against a screw 15 of the main setting shaft 2 turns the shaft 2 in a manner that by way of the pull bar 9 the ball head 12 of the stitch setting lever 10 comes to rest against the cam 13 at A. A bridge 17 is rotataby mounted around the auxiliary setting shaft 3 for the auxiliary feed dog 38 and presents a linkage arm 17a which is connected by way of a connecting bar 18 with the other arm of the double armed lever 8.

' Setting screws 19 and 24 are threadedly mounted in the bridge 17 which is journalled on the auxiliary setting shaft 3 to provide special adjusting possibilities for the shaft 3 of the auxiliary feed dog 38 which permit differentiating between the feed lengths of the feed dogs relative to one another. These screws 19 and 20 cooperate as pressure transmitting members with a two armed pressure receiving abutment member 21. A coupling spring 23 biased at one end against a ring 22 mounted on the setting shaft 3 and at the other end against the bridge 17 turns the shaft 3 in a manner that one arm of the abutment member 21 comes to rest against the counter abutment or screw 19.

The coupling spring 23 between the bridge 17 of the linkage means that is rotatably mounted on the auxiliary setting shaft 3 and a linkage connecting member such as a ring 22 fixed in position on the setting shaft 3, applies a force opposite to the effective force of torque spring 16. Thus by reversing the direction of feed of the two feed dogs by pressing down on a bar tacking finger 24 which is secured to the setting shaft 11 which is journalled in the standard of the machine, it is necessary in order to turn the setting shafts to overcome the force of only one spring 16. That is because the coupling spring 23 effects by itself the force transmitting engagement of the abutment 21 secured to the setting shaft 3 for the auxiliary feed dog 38 with the screw 20 arranged on the gear- Hereinafter the drive means and the means for varying the magnitudes of feed for the main feed dog and for the auxiliary feed dog are described, which are identical in both embodiments. While these mechanisms do not directly concern the subject of the application, the description thereof is believed to be desirable as it contributes to the better understanding of the invention.

In the base plate 1 parallel to the setting shafts 2 and 3 or 102 and 103, respectively, a further shaft 27 is rotatably journalled. This shaft is driven in a manner not illustrated by way of a belt connected to the arm shaft of the machine. Cams 28, 29 are secured to the shaft 27, and they are encompassed by cam bars 38, 31, respectively.

Parallel to and spaced from the shaft 27, two coaxially arranged shafts 32, 33 are journalled in the base plate 1. The inner shaft 33 extends partly from the shaft 32. The forked lever 34 is firmly connected with the shaft 32, and the main feed dog 35 is linked thereto by means of the feed dog bar 36. The forked lever 37 is firmly connected to the shaft 33, and the feed bar 39 which is provided with the auxiliary feed dog 38 is connected thereto. The feed bars 36, 39 each have a forked end 40, 41, respectively, into which extend lifting cams 43, 44, respectively, which are secured to the shaft 42. As the shaft 42 rotates, the lifting cams 43, 44 impart the required lifting movements to the feed dogs 35, 38.

Two guide links 46, 47 are linked to the cam bar 38 by means of a bolt 45. The guide link 46 is rotatably connected by means of a bolt 48 with a lever49 which is secured upon the setting shaft 2 or 182 of the main feed dog 35. The guide link 47 is rotatably fastened by means of a bolt 50 to a lever 51 which is secured at its hub upon the shaft 32 of the main feed dog 35.

Two guide links 53, 54 are linked to the cam bar 31 by means of a bolt 52. The guide link 53 is rotatably connected by means of a bolt 55 with a lever 56, which in turn is fastened to the auxiliary setting shaft 3 or 1113 of the auxiliary feed dog 38. The guide links 54 is rota ably secured by means of a bolt 57 to a lever 58 which is secured at its hub upon the shaft 33 of the auxiliary feed dog 38. As shown in FIG. 4, the levers 49, 58 and guide links 46, 47 and 53, 54 have the same effective length.

In the second embodiment illustrated by FIG. 3, a hollow shaft 130 provided with a. pawl 129 is arranged upon and fixedly secured to a stitch setting shaft 111 journalled in the standard of the machine. tened to this hollow shaft, to the end of which a ball headed draw bar 128 is linked which is connected to one arm of a linkage connecting member in the form of a two armed lever 127 that is secured to the auxiliary setting shaft 103 which is journalled in the work plate. A second hollow shaft 133 is journalled on the hollow shaft 130 and is provided with a pawl or abutment member 132 and has fastened thereto a two armed stitch setting lever 110, one arm of which extends with the ball headed end 112 into the cam of a setting disk 14 arranged laterally of the standard of the machine for controlling the feed length of the feed dogs in the manner illustrated in FIG. 2. At the end of the other arm of the stitch setting lever 110 a ball headed draw bar 109 is linked with one arm of linkage connecting means including a two armed lever 108 that is fixedly secured .to the main setting shaft 102 journalled in the work plate. A pressure spring 116 biased at one end against the work plate and at the other end against the other arm of lever 198 turns the setting shaft 102 for the main feed dog 35 with the associated lever gearing in a manner that the ball headed end 112 of the arm of the stitch setting lever 110 engages the cam of setting disk 14.

One arm of lever 108 and arm 127a of double armed lever secured to setting shafts 102 and 103, respectively, are linked with one another by means of a coupling A crank 131 is fastion.

spring 123 which tends to turn the shafts 102 and 103 with their associated linkage in opposite directions. This is prevented, however, in that upon the hollow shaft 136 a limiting or abutment member 134 is rotatably mounted which is provided with two abutment screws 119 and 128, which are disposed in the path of movement of the pawl or abutment member 132 secured to the hollow shaft 133. Two overload straps 136 which are connected with one another by a tension spring 135 are journalled in the limiting member 134 and press the pawl 129 fixed upon hollow shaft 130 into corresponding position with the abutment 137 provided upon the limiting member. At the same time the overload straps 136 engage the abutment 137 of the limiting member 134 under the influence of spring 135 and thus keep the projecting end of pawl 129 in alignment with the abutment 137 (FIGS. 3, 5). The coupling spring 123 turns the setting shaft 103 for the auxiliary feed dog 38 in a manner that the abutment screw 120 engages the pawl 132 which is secured to the hollowshaft 133.

When the bar tacking lever 124 which is mounted upon the adjusting shaft 111 at the front of the standard is pressed downwardly to reverse the direction of feed of both feed dogs to tack the seam by means of a few reverse stitches, it is only necessary to overcome the force of the torsion spring 116, because the coupling spring 123 merely turns the setting shaft 103 into the same angular position as that of setting shaft 182 with respect to abutment 1219-132.

The two installations that are shown as exemplary embodiments operate as follows: FIG. 4 shows the position of the linkage system for the zero position of the feed dogs 35, 38. In this position the junction of levers 49 or 56 defined by the bolts 48, 50 or 55, 57 is located at the guide links 46, 47 and 53, 54 in the projected imaginary axes of rotation 48, 50 and 55, 57. Owing to the reciprocating movement of the cam bars 38 and 31 during the running of the machine, the guide guide links 46, 47 and 53, 54 are pivotally moved about these axes of rota- Since the junction 50 or 57 is in alignment with the axes of rotation, no movement of the guide link 47 or 54 is transmitted to the lever 51 or 58, so that they as well as the shafts 32 and 33 are at a standstill.

If for adjusting the magnitude of feed the setting disk 14 (FIG. 2) is rotated manually ill]. a clockwise direction, then also the two setting shafts 2, 3 or 102, 103 rotate correspondingly by way of the associated linkage connections and thus assume the same angular position. Each setting shaft is associated with a guide link system. The axis of rotation 48 or 55 of the particular guide link system is adjusted by Way of lever 49 or 56 with respect to the junction 50 or 57, so that with the reciprocating movement of the cam bar'30 or 31 the guide link 46 or 53 effects a true rotary movement about the axis of rotation 48 or 55, while the guide link 47 or 54, besides being subject to this rotary movement, is also subjected to a lifting or thrust movement. This thrust movement causes the lever 51 or 58 to effect a pivotal movement about the shaft 32 or 33. The more the setting disk 14 is rotated clockwise, the greater will be the distance between the axis of rotation 48 or 55 from the junction 50 or 57, and the greater will be the oscillating movement of the shaft 32, 33 and thus of the movement of the feed dogs 35, 38. In this manner the feed dog movement can be adjusted in a continuous manner. The two feed dogs effect movements of the same magnitude.

If the auxiliary feed dog is to effect a greater forward movement for shining the material, then the setting in the arrangement in accordance with FIG. 2' can be effected by means of setting screws 19, 20 below the base plate and in the arrangement in accordance with FIG. 3 with the setting screws 119, 120-above the base plate. By turning the setting screw 20 or 120 forward and turning back the screw 19 or 119, the angular position of the shaft 3 or 103 and the position of the guide link 53 are such that the guide mechanism 52-58 imparts to the auxiliary feed dog 38 a feed movement which is greater than that of the main feed dog 35. Both of the coupling springs 23 or 123 of these arrangements press the setting shaft for the auxiliary feed dog against an adjustable abutment.

If a predetermined maximum feed length is temporarily desired for the auxiliary feed dog, then it is possible by suitably turning back the set screws 19 or 119 to adjust the magnitude of feeding. The maximum feed length is set by pressing down a pedal to which the draw bar 26 is linked which co-operates with a crank lever 25 which is secured to the setting shaft for the auxiliary feed dog. The coupling spring 23 or 123 after release of the pedal reestablishes the original condition.

A stretching effect of the material is obtained in that the screw 20 or 120 is turned back and screw 19 or 119 is adjusted correspondingly. The angular position of the setting shaft 2 or 102 and the setting of the guide link 46 then are such that the guide mechanism 46-51 imparts a feeding movement to the main feed dog 35 that is greater than that of the auxiliary feed dog 38.

For tacking the seam at the beginning or at the end, the operating bar 24 or 124 is pressed against the pressure of spring 16 or 116, and thus the setting shafts for the main feed dog and for the auxiliary feed dog are rotated to such an extent by way of the connecting gear of the setting shafts that their direction of feed is reversed.

Having now described our invention with reference to the embodiments illustrated in the accompanying drawings, we do not wish to be limited thereto, but what we desire to protect by Letters Patent of the United States is set forth in the appended claims.

We claim:

1. Mechanism for controlling the cooperation of a main feed dog and of an auxiliary feed dog to adjust the differential feed of a sewing machine, said mechanism comprising a main setting shaft for a main feed dog and an auxiliary setting shaft for an auxiliary feed dog, linkage means including a linkage connecting member for each said shaft, each disposed in fixed position on its respective shaft, and a linkage arm for each shaft, linkage connecting said linkage arms for transmitting movement from one said shaft to the other, an abutment member having at least one arm operatively associated with said linkage means, a stitch setting shaft including an operating bar and a stitch setting lever arm mounted on said stitch setting shaft and having an arm linked to said main setting shaft, a biasing spring imparting bias to said main setting shaft in one direction, a coupling spring arranged in said linkage means between said connecting members of said shafts and biasing said auxiliary dog setting shaft in a direction opposite to the bias of said main shaft, said coupling spring having at least one end in engagement with one said connecting member, and abutment means including said at least one arm of said abutment member and adjustable abutment means biased by said coupling spring by way of said linkage means into force transmitting engagement with said one arm and compelling said auxiliary shaft to follow the movements of said main setting shaft.

2. Mechanism for controlling the cooperation of a main feed dog and of an auxiliary feed dog to adjust the differential feed of a sewing machine, said mechanism comprising a main setting shaft for a main feed dog and an auxiliary setting shaft for an auxiliary feed dog, linkage means including a linkage connecting member for each said shaft, each disposed in fixed position on its respective shaft, and a linkage arm for each shaft, linkage connecting said linkage arms for transmitting movement from one said shaft to the other, an abutment member having at least one arm operatively associated with linkage means, a stitch setting shaft including an operating bar and a stitch setting lever arm mounted on said stitch setting shaft and having an arm linked to said main setting shaft,

a biasing spring imparting bias to said main setting shaft in one direction, a coupling spring arranged in said lnkage means between said connecting members of said shafts and biasing said auxiliary dog setting shaft in a direction opposite to the bias of said main shaft, said coupling spring having at least one end in engagement with one said connecting member, and abutment means including said at least one arm of said abutment member and adjustable abutment means biased by said coupling spring by way of said linkage means into force transmitting engagement with said one arm and compelling said auxiliary shaft to follow the movements of said main setting shaft, said coupling spring being a helical spring having one end connected to the connecting member of said auxiliary setting shaft and the other end to said abutment means, and said abutment means being disposed around said auxiliary setting shaft.

3. Mechanism for contnolling the cooperation of a main feed dog-and of an auxiliary feed dog to adjust the differential feed of a sewing machine, said mechanism comprising a main setting shaft for a main feed dog and an auxiliary setting shaft for an auxiliary feed dog, linkage means including a linkage connecting member for each said shaft, each disposed in fixed position on its respective shaft, and a linkage arm for each shaft, linkage connecting said linkage arms for transmitting movement from one said shaft to the other, an abutment member having at least one arm operatively associated with said linkage means, a stitch setting shaft including an op erating bar and a stitch setting lever arm mounted on said stitch setting shaft and having an arm linked to said main setting shaft, a biasing spring imparting bias to said main setting shaft in one direction, a coupling spring arranged in said linkage means between said connecting members of said shafts and biasing said auxiliary dog setting shaft in a direction opposite to the bias of said main shaft, said coupling spring having at least one end in engagement with one said connecting member, and abutment means including said at least one arm of said abutment member and adjustable abutment means biased by said coupling spring by way of said linkage means into force transmitting engagement with said one arm and compelling said auxiliary shaft to follow the movements of said main setting shaft, said connecting members being in the form of double armed levers and said coupling spring extending between proximate arms of said levers on one side of said shafts and said abutment member being disposed around said stitch setting shaft.

4. Mechanism for controlling the cooperation of a main feed dog and of an auxiliary feed dog to adjust the differential feed of a sewing machine, said mechanism comprising a main setting shaft for a main feed dog and an auxiliary setting shaft for an auxiliary feed dog, linkage means including a linkage connecting member for each said shaft, each disposed in fixed position on its respective shaft, and a linkage arm for each shaft, linkage connecting said linkage arms for transmitting movement from one said shaft to the other, an abutment member having at least one arm operatively associated with said linkage means, a stitch setting shaft including an operating bar and a stitch setting lever arm mounted on said stitch setting shaft and having an arm linked to said main setting shaft, a biasing spring imparting bias to said main setting shaft in one direction, a coupling spring arranged in said linkage means between said connecting members of said shafts and biasing said auxiliary dog setting shaft in a direction opposite to the bias of said main shaft, said coupling spring having at least one end in engagement with one said connecting member, and abutment means including said at least one arm of said abutment member and adjustable abutment means biased by said coupling spring by way of said linkage means into force transmitting engagement with said one arm and compelling said auxiliary shaft to follow the movements of said main setting shaft, said abutment means associated with said auxiliary setting shaft being adjustable to limit the minimum and the maximum feed of the auxiliary feed dog.

5. Mechanism for controlling the cooperation of a main feed dog and of an auxiliary feed dog to adjust the diflerential feed of a sewing machine, said mechanism comprising a main setting shaft for a main feed dog and an auxiliary setting shaft for an auxiliary feed dog, linkage means including a linkage connecting member for each said shaft, each disposed in fixed position on its respective shaft, and a linkage arm for each shaft, linkage connecting said linkage arms for transmitting movement from one said shaft to the other, an abutment member operatively associated with said linkage means, a stitch setting shaft including an operating bar and a stitch setting lever arm mounted on said stitch setting shaft and having an arm linked to said main setting shaft, a biasing spring imparting bias to said main setting shaft in one direction, a coupling spring arranged in said linkage means between said connecting members of said shafts and biasing said auxiliary dog setting shaft in a direction opposite to the bias of said main shaft, said coupling spring having at least one end in engagement with one said connecting member, and abutment means comprising a double armed abutment member mounted on said auxiliary shaft and adjustable abutment means biased by said coupling spring into force transmitting engagement with said abutment member and compelling said auxiliary shaft to follow the movements of said main setting shaft.

References Cited by the Examiner UNITED STATES PATENTS 2/44 Knaus 112 209 2/57 Hess 112209 

1. MECHANISM FOR CONTROLLING THE COOPERATION OF A MAIN FEED DOG AND OF AN AUXILIARY FEED DOG TO ADJUST THE DIFFERENTIAL FEED OF A SEWING MACHINE, SAID MECHANISM COMPRISING A MAIN SETTING SHAFT FOR A MAIN FEED DOG AND AN AUXILIARY SETTING SHAFT FOR AN AUXILIARY FEED DOG, LINKAGE MEANS INCLUDING A LINKAGE CONNECTING MEMBER FOR EACH SAID SHAFT, EACH DISPOSED IN FIXED POSITION ON ITS RESPECTIVE SHAFT, AND A LINKAGE ARM FOR EACH SHAFT, LINKAGE CONNECTING SAID LINKAGE ARMS FOR TRANSMITTING MOVEMENT FROM ONE SAID SHAFT TO THE OTHER, AN ABUTMENT MEMBER HAVING AT LEAST ONE ARM OPERATIVELY ASSOCIATED WITH SAID LINKAGE MEANS, A STITCH SETTING SHAFT INCLUDING AN OPERATING BAR AND A STITCH SETTING LEVER ARM MOUNTED ON SAID STITCH SETTING SHAFT AND HAVING AN ARM LINKED TO SAID MAIN SETTING SHAFT, A BIASING SPRING IMPARTING BIAS TO SAID MAIN SETTING SHAFT IN ONE DIRECTION, A COUPLING SPRING ARRANGED IN SAID LINKAGE MEANS BETWEEN SAID CONNECTING MEMBERS OF SAID SHAFTS AND BIASING SAID AUXILIARY DOG SETTING SHAFT IN A DIRECTION OPPOSITE TO THE BIAS OF SAID MAIN SHAFT, SAID COUPLING SPRING HAVING AT LEAST ONE END IN ENGAGEMENT WITH ONE SAID CONNECTING MEMBER, AND ABUTMENT MEANS INCLUDING SAID AT LEAST ONE ARM OF SAID ABUTMENT MEMBER AND ADJUSTABLE ABUTMENT MEANS BIASED BY SAID COUPLING SPRING BY WAY OF SAID LINKAGE MEANS INTO FORCE TRANSMITTING ENGAGEMENT WITH SAID ONE ARM AND COMPELLING SAID AUXILIARY SHAFT TO FOLLOW THE MOVEMENT. OF SAID MAIN SETTING SHAFT. 